Prostaglandin E2 production by the cattle tick ( Boophilus microplus) into feeding sites and its effect on the response of bovine mononuclear cells to mitogen

Prostaglandin E2 (PGE2) secretion by the cattle tick Boophilus microplus into feeding sites was quantified. It was detected by the in vitro tube feeding experiment and it was determined that a semi-engorged female tick could produce and transmit 1.8 ng PGE2 into the feeding site. Using the in vitro membrane feeding system, newly molted adult ticks were also shown to secrete 0.04–0.15 ng PGE2 into the feeding site; however, female ticks produced more PGE2 than male ticks. The immune suppressive effect of PGE2 in the saliva of B. microplus on the bovine mononuclear cells (MNC) was also examined. PGE2 in the saliva was suspected of being a major component that inhibited the blastogenic response of MNC to a T-cell mitogen phytohemagglutinin. As bovine MNC are sensitive to low level concentration of PGE2, the PGE2 transmitted into feeding sites was suspected to be sufficient to produce physiological effects on the bovine host.